1-2% of the world's population have red hair. So, we're giving the phenomenon its own episode! Today, we discuss the gene/protein that causes red hair, as well as its psychological and possible medical effects... Sources for this episode: Bryant, NIH Research Matters (2021), Study finds link between red hair and pain threshold (online) (Accessed 12/01/2024). Gradwohl, S. C., Aranake, A., Abdallah, A. B., McNair, P., Lin, N., Fritz, B. A., Villafranca, A., Glick, D., Jacobsohn, E., Mashour, G. A. and Avidan, M. S. (2015), Intraoperative awareness risk, anesthetic sensitivity, and anesthetic management for patients with natural red hair: a matched cohort study. Canadian Journal of Anesthesia 62: 345 355. Massachusetts General Hospital, Science Daily (2021), Research reveals why redheads have different pain thresholds (online) (Accessed 12/01/2024). Regan, K. O. (2014), “Red hair in popular culture and the relationship with anxiety and depression”. Thesis submitted for University College, Cork. Rees, J. L. (2000), The Melanocortin 1 Receptor (MC1R): More Than Just Red Hair. Pigment Cell Research 13: 135-140. Robinson, K. C., Kemény, L. V., Fell, G. L., Hermann, A. L., Allouche J., Ding, W., Yekkirala, A., Hsiao, J. J., Su, M. Y., Theodosakis, N., Kozak, G., Takeuchi, Y., Shen, S., Berenyi, A., Mao, J., Woolf, C. J. and Fisher, D. E. (2021), Reduced MC4R signalling alters nociceptive thresholds associated with red hair. Science Advances 7: eabd1310. Author unknown, Wikipedia (date unknown), Nociception (online) (Accessed 12/01/2024). Author unknown, Worldometer (date unknown), World Population Clock: 8.1 Billion People (LIVE, 2024) (online) (Accessed 11/01/2024).